A number of Microsoft online services, including Hotmail, MSN, Office 365, and seemingly most if not all of *.live.com addresses are currently “experiencing an outage”. MSN and Office 365 have already tweeted about it:

The downtime, which happened on Friday at about 4am in the UK — 8pm on Thursday Pacific time (PDT) — was due to a domain name service problem, according to Microsoft.

But Microsoft certainly isn't alone.Google has also seen its share of downtime. Just this past Wednesday, Google Docs was offline for about 30 minutes. In May, the company's Blogger service was unavailable for the greater part of a day.